All Things Gypsum
A New Edition of GA-216A new edition of Application and Finishing of Gypsum Panel Products, GA-216 was published in early August. The revised document contains a number of changes from the 2007 edition. To assist in your understanding of the newest edition of GA-216, we’ll take the time to summarize and discuss some of the most significant modifications.
The primary change eliminates two entire sections of the document: Section 15 on “Application of Gypsum Panel Products to Receive Adhesively Applied Ceramic or Plastic Wall Tile or Plastic Finished Wall Panels” and the supplementary Appendix section A.1 on “Application of Ceramic or Plastic Finished Wall Panels over Gypsum Panel Products.” Both sections addressed the use of water-resistant gypsum backing board (“greenboard”) as a substrate for ceramic and plastic tile and panels in wet areas, such as tub and shower enclosures and surrounds. Modifications to model building codes that eliminated the ability to use greenboard as a backing for tile in wet areas made both sections obsolete.
The outright removal of Appendix A.1 from GA-216 caused a problem, however, because it eliminated prescriptive language that detailed the process for finishing gypsum panels in non-wet areas that are to receive ceramic or plastic tile - an installation that is still permitted by model building codes. To address the issue, the Gypsum Association Technical Committee inserted a reference in Appendix A.3 of GA-216 to the American National Standard Specification for the Installation of Ceramic Tile, ANSI A 108. The A108 standard prescribes a process for the treatment of gypsum panels that are to receive tile and defines a method for the application of ceramic tile.
Another significant modification occurs in Section 2. The previous edition indicated that the specification was appropriate for use with gypsum panels manufactured to the ASTM C 1396; C 1278; and C 1178 standards: in order, gypsum board, fiber-reinforced gypsum panels, and glass-mat water-resistant gypsum backing panels. The 2010 version eliminates the C 1178 reference and adds a reference to ASTM C 1658, Standard Specification for Glass Mat Gypsum Panels. Similar to what recently occurred in gypsum board product standards when multiple individual standards were combined to create ASTM C 1396, the change reflects the creation of the new multi-product C 1658 standard.
Subtle changesSome changes to the specification are subtle and relatively inconsequential. For example, Section 220.127.116.11. (previous Section 18.104.22.168.), was changed to eliminate the phrase “not less than 25 gauge” and include “not less than 0.0179 in. steel” when describing steel studs. The change was made so that GA-216 reflects recent nomenclature changes contained in steel stud manufacturing standards.
A minor change that is important is the modification to Section 4.6.2., where the section now incorporates a specific distance recommendation for joints between panels that occur adjacent to openings. The 2007 edition of GA-216 specified that “… joints shall be located so that no joint will align with the edge of an opening unless control joints are to be installed …” The language was changed to incorporate a specific distance prohibition for joint placement: “… no joint shall occur within 12 inches of the corner of an opening unless control joints are to be installed …”
The effect of the change is two-fold. One, it clarifies the section. The previous language was being incorrectly interpreted as a requirement to install a control joint between panels when the joint between panels was installed parallel to, but a significant distance from, the framed opening. Two, the new specific distance requirement prohibits an applicator from installing an unprotected joint between panels immediately adjacent to the edge or corner of an opening. Unfortunately, stories abound about applicators that would place a joint between panels only a couple of inches away from the corner of a door that, after a few slams of the door, would crack. Noting that the panel joint “did not align with the edge of the opening” the installer would also conveniently neglect to install a control joint at the same location.
Table talkA number of tables have been relocated to place them closer to the charging text and some table footnotes have been cleaned up. Footnote A to Table 1 contains a minor change that clarifies panel installation requirements when water-based texture is installed on a ceiling. The same change occurs in other tables that address application panel to ceilings. A change that looks significant at first glance, the new text in Section 4.6.4., is actually a simple format change that extracts repetitive language from previous sections 5, 6, and 8, and places it into a single location where it can serve as general charging language.
Other changes include:
The addition of language in Section 4.6.10 clarifying the minimum distance that must be maintained between a protected exterior finished grade or the ground in a crawl space and the bottom end or edge of a gypsum panel. The added language makes GA-216 consistent with other gypsum panel application standards.
Section 15 (previously Section 16) added language acknowledging the use of plastic beads for protecting the edge of outside corners, arches, and curves.
The addition of language to Section 18 that describes the method of application of three common types of joint tapes: paper tape; self-adhering glass mesh tape; and glass mesh tape that is not self-adhering. The information on glass mesh tape did not appear in a previous edition.
These are simply some of the highlights of the changes to GA-216 and the list discussed herein is by no means complete. The new edition of the document should be reviewed to determine other modifications that might be of interest to an applicator. Note that the reference to the document in the International Building Code will not be updated until the next edition of the code becomes available in 2012. Other documents that reference GA-216 will be updated to reflect the new edition as they are revised.
Copies of the new edition of GA-216 are available from the Gypsum Association at www.gypsum.org.
Michael Gardner is the executive director of the Gypsum Association, an international trade association representing gypsum board manufacturers in the United States and Canada.